1. Field of Invention
Exemplary embodiments of the present invention relate to a lighting unit suitable for illuminating a spatial light modulation device such as a liquid crystal light valve and a projector including the lighting unit.
2. Description of Related Art
The related art includes a lighting unit for a liquid crystal projector which includes splitting and superposing devices to split a luminous flux from a lamp device having a lamp and a parabolic mirror into a plurality of partial luminous fluxes and to superpose those on an illuminated area. According to the lighting unit of this type, the splitting and superposing devices additionally contain such a device as an afocal optical system to narrow a width of luminous flux. The afocal optical system decreases an angle of incidence of each partial luminous flux which reaches the illuminated area to enhance utilization efficiency of illumination light, as disclosed in related art document JP-A-11-212023.